Association between maternal HBV-DNA levels and pregnancy outcomes among hepatitis B carriers: a retrospective cohort study in China

The relationship between maternal hepatitis B virus (HBV) DNA load and pregnancy outcomes remains inconsistent. Clarifying this association, including the potential dose-response relationship, is important for improving prenatal management. A retrospective study was conducted in a single-center cohort of 1,020 HBsAg-positive pregnant women. Participants were categorized by HBV-DNA load, and associations with pregnancy outcomes were assessed using multivariate logistic regression. Sensitivity analyses included multiple imputation for missing data and exclusion of women who received antiviral therapy during pregnancy. The mean age was 32.51 ± 4.75 years, and the mean pre-pregnancy BMI was 21.43 ± 3.07 kg/m². Most participants were multiparous (67.65%) and had a gravidity ≥ 2 (77.16%). After full adjustment for covariates, women in the highest HBV-DNA load group (Group 3) had a higher risk of preterm birth than those in the lowest group (Group 1) (Odds ratio (OR): 5.36; 95% Confidence interval (CI): 2.43–11.82; P < 0.001). Median HBV-DNA levels were higher in the preterm birth group than in the non-preterm group. Restricted cubic spline analysis showed a positive association between maternal HBV-DNA load and preterm birth risk. This study found that high maternal HBV-DNA load was associated with an increased risk of preterm birth. These findings support the potential clinical value of prenatal HBV-DNA quantification in identifying pregnancies at high risk of preterm birth and enabling timely risk stratification and individualized management.